Jesus was criticised in the first century AD by the Pharisees and scribes for disobeying certain halakhic interpretations of the Mosaic Law, for example by healing on Sabbath. He was decried in Judaism as a failed Jewish messiah claimant and a false prophet by most Jewish denominations. Judaism also considers the worship of any person a form of idolatry, and rejects the claim that Jesus was divine. Some psychiatrists, religious scholars and writers explain that Jesus' family, followers (John 7:20) and contemporaries seriously regarded him as delusional, possessed by demons, or insane.

Early critics of Jesus and Christianity included Celsus in the second century and Porphyry in the third. In the 19th century, Friedrich Nietzsche was highly critical of Jesus as described in the New Testament, whose teachings he considered to be "anti-nature" in their treatment of topics such as sexuality. More contemporary notable critics of Jesus include Ayn Rand, Hector Avalos, Sita Ram Goel, Christopher Hitchens, Bertrand Russell, and Dayananda Saraswati.

The Pharisees and scribes criticized Jesus and his disciples for not observing Mosaic Law. They criticized his disciples for not washing their hands before eating. (The religious leaders engaged in ceremonial cleansing like washing up to the elbow and baptizing the cups and plates before eating food in them—Mark 7:1–23, Matthew 15:1–20.) Jesus is also criticized for eating with the publicans (Mark 2:15). The Pharisees also criticized Jesus' disciples for gathering grain on the Sabbath (Mark 2:23–3:6).

There was some disagreement in the early church about the inclusion of Gentiles, including the status of the Mosaic covenant (called the Old Covenant by Christians) and whether Christians are still bound by it. Paul the Apostle believed that the New Covenant had superseded the old, and that Christians were no longer bound by all parts of the latter. His views, called Pauline Christianity, would become dominant in the following centuries, with most Christian denominations today believing that Jesus released his followers from the obligation to follow Mosaic Law in its entirety.

Throughout the four canonical gospels, Jesus is characterised by his claim to divine authority as Messiah, variously either entrusting his disciples to keep this status a secret (as in Mark) or openly proclaiming (as in John) his status and his mission. Only in the Gospel of John does Jesus emphatically claim divinity, and not just divine authority, through the seven statements of "I am". In the gospel, it is this claim which leads to some of the Jews attempting to stone him, and their eventual handing Jesus over to Pilate for crucifixion on charges of blasphemy:

"We are not stoning You for any good work," said the Jews, "but for blasphemy, because You, who are a man, declare Yourself to be God."

— Gospel of John 10:33

Elsewhere in the gospels, Jesus makes multiple claims of divine authority, ability to cast out demons, authority to forgive sins, and that spiritual peace and salvation were to be found in the acceptance of his leadership. The claims caused controversy among the local Jewish community, as anyone making claims like these are false prophets per several verses in Deuteronomy.